Travelling propping machine



8 1967 HANS-SIEGFRIED KEIL TRAVELLING PROPPING MACHINE 2 Sheets-Sheet 1 Filed Aug. 31, 1964 INVEN7UR HANS-SIEGFRIEI] KEIL 8- 1, 1967 HANS-SIEGFRIED KEIL 3,333,424

TRAVELLING PROPPING'MACHTNE Filed Aug. 51, 1964 2 Sheets-Sheet 2 INVENTOR HANS-SIEBFRIED KEIL 8 1&8 mm 8 m @538 Q u m w United States Patent 3,333,424 TRAVELLING PROPPING MACHINE Hans-Siegfried Keil, Altlunen, Westphalia, Germany, assignor to Gewerkschaft Eisenhutte Westfalia, Wethmar, near Lunen, Westphalia, Germany, a corporation Filed Aug. 31, 1964, Ser. No. 393,446

Claims priority, application Germany, Sept. 2, '1963,

12 Claims. (Cl. 61-45) This invention relates in general to propping machines, and more particularly to hydraulically, or pneumatically driven propping machines which are capable of step-wise travelling motion, and providing progressive support for a roof surface, such as in mining excavations.

The travelling propping machine of the invention, as well as those of the prior art, utilizes at least two parallelly advancing propping frames for supporting the roof of an excavation, with said propping frames being driven by hydraulic or pneumatic actuation means. In a typical mining operation using travelling propping machines, the propping frames are extensibly jacked to support a section of the excavation roof. As the excavation progresses, it is necessary that those portions of the roof in the direction of excavation be successively supported, and thus the propping machine must be made to travel in the direction of excavation, and at the same time, provide sufficient support to prevent the roof from collapsing over the propping machine, and the equipment and workmen near-by in front of it. It is common practice to permit the roof in back of the propping machine to collapse since the forward excavation area is supported by one or more propping machines and is accessible from side tunnels which are provided.

To provide support for the roof while the propping machine is advanced, one of the propping frames is held stationary, supporting a portion of the roof, while the other is released, or jacked down, and advanced by the drive actuation means, usually a hydraulic cylinder. When the one frame has 'been advanced as far as possible, it is jacked up to support the roof, and the advancing operation is repeated with the other frame. Thus the prop-ping machine advances step-wise, and provides support for progressive roof sections.

In the propping machines of the prior art, the length of each step was inherently limited by the length of the hydraulic cylinder. For a given excavation travel distance, a large number of steps had to be made, which was particularly disadvantageous because with each removal and resetting of the propping frames, the roof was disturbed, and the hazard of collapse was increased.

Thus, it is particularly advantageous to provide as large a step as possible in a travelling propping machine, especially in those that are to be used in conjunction with pneumatic coal, or ore loading equipment.

An increased step length in propping machines has been provided hitherto by disposing two actuating cylinders in tandem, so that their stroke lengths add up. It has also been proposed to increase the step length of such propping machines by means of suitable cable pulling devices.

The invention is therefore directed at the problem of providing a simple method of increasing the step length in such machines, and with a minimum modification to the basic construction of conventional parallelly advancing propping machines, and without changing to any considerable extent the basic dimensions of actuating cylinders and pistons. Furthermore, in the invention, the disadvantage existing in prior art machines of this kind, namely, that the length of the advancing cylinders and hence the piston stroke is what ultimately determines the length of the step, is eliminated.

The propping machine in accordance with the invention solves the aforesaid problem by coupling the parallelly progressing propping frames with a parallel guiding means as well as with a hydraulic cylinder which articulately joins the two propping frames of the machine so that the floor frame thus formed is collapsible, to facilitate transportation.

In the basic machine, two propping frames progress parallelly to each other and are coupled by a parallel guiding means and a hydraulic cylinder which advances them. One frame is connected to a piston shaft on which a double-acting hydraulic cylinder is carried in a longitudinally displaceable manner, and this cylinder is connected by appropriate means to a guide rail affixed to the other frame. The guide rail is longitudinally moveable in relation to the cylinder, and can be locked in place by clamping means associated with the cylinder connecting means.

When both frames are locked, i.e. extensibly jacked between the floor and the roof, the cylinder when suitably powered, can travel back and forth along the piston shaft and guide rail by a stroke length. If one of the frames is to be advanced, as for example, the frame with the guide rail, the cylinder is unclamped and made to recede away from the direction of advance until it is blocked by the piston. Then the cylinder is clamped to the guide rail, and the guide rail frame is unlocked. With the piston shaft frame remaining locked, hydraulic power is applied to drive the cylinder and guide rail frame forward by a stroke length. Then the cylinder is unclamped and driven back again and locked to the guide rail. Hydraulic power is then applied to drive the cylinder and guide rail frame forward by another stroke length. This procedure is repeated until with successive stroke movements the cylinder cannot be receded any further because it is against the rear limit end of the guide rail.

To advance the piston shaft frame, the same procedure is used. The guide rail frame is locked and the piston shaft frame is released. Hydraulic power is applied-to the cylinder which is clamped to the guide rail, to drive the piston and its frame forward by one stroke length. Then the cylinder is unclamped and advanced on the guide rail by one stroke length where it is blocked by the piston. At that position, the cylinder is again clamped and the piston frame is driven forward by another stroke length. This procedure is repeated until the cylinder cannot he advanced any further because it is against the forward limit end of the guide rail. i

It should be noted that the length of the guide rail can be adapted to meet the needs of each particular application, without requiring any substantial structural modifications on standard propping frames.

The clamping system for locking the cylinder on the guide rail can be operated by hand, as in conventional mechanical locking mechanisms or, if desired, can be operated by a conventional hydraulically powered mechanism which can be synchronized with the application of hydraulic power to the cylinder, so that the cylinder is alternately clamped and released in accordance with the aforementioned advancing procedure.

The guide rail or guiding means can be provided by a variety of conventional guide means, such as cylindrical bars, rods, or even slotted members, and engaging means such as catches, cams, teeth or grooves for engaging corresponding cl'amping parts may be used.

In accordance with another feature of the invention as described in detail hereinafter, the guide rail which is clamped to the cylinder is made relatively long in relation to the cylinder length, such as for example, three or more strokes are required per step length, so that in applications where several strokes are acceptable for advancing one of the two frames, the cylinder can be made very short, so that the travel range of the frames is relatively unencumbered by the cylinder and its associated hydraulic lines,

According to an additional embodiment of the invention, a propping machine is provided with a plurality of individually advanceable propping frames, which can creep along on guiding rails independently of one another. Where these guiding rails are placed against a conveyor, such as is used for removing coal which is cut loose by a coal plane machine, and the guide rails are held fixed in relation to the floor and roof of a mining excavation by means of a separate prop or propping frame associated therewith, the advanceable frames can simultaneously hear an advancing system for the conveyor, or can themselves form such a system, and the propping frames which move along the guide rails can be equipped with two prop jacking members, as desired, so that with the long steps obtainable with the invention, no frame cap is required to repeatedly support the same roof area. Thus, the difficulties associated with the excessively frequent propping and unpropping of the roof, as with the machines of the prior art, are avoided.

As already mentioned, the guiding rail itself can also form a prop frame, or bear a cap at its working face end, preferably set crosswise to the direction of progress, so as to cause a clear determination of the excavation cleavage area. Such an arrangement provides a triangular roof propping, which is advantageous in mining, since only small roof areas are released progressively and each of the frames can be constructed to have as long a step as desired, since the roof is never propped twice at the same point.

The guide rails, although they do not necessarily have to use the conveyor for support, can accompany the lateral shifts of the conveyor as the excavation advances, thus enabling the entire propping system to follow and be straightened out.

According to another feature of the invention which utilizes a plurality of propping machine elements connected together, the guide rails of the individual machines may be connected together by a common connecting member, or individual connecting rods so that all the guide rails are kept mutually parallel over the length of the excavation Working face. As desired, the cleavage line, the rear wall of the excavation and the pneumatic loading apparatus or conveyor can remain fixed in place until all the guide rails are advanced together, as the excavation progresses.

Other variations of the invention, such as guide rails which are in the form of telescoping members, can be used, so that said guide rails can be advanced independently of the associated conveyor, so that the entire length of the conveyor can be shifted as the excavation progresses.

It is immaterial to the invention whether the clam-ping means carried on the rail is fastened directly to the cylinder or to the piston shaft, since the same net result can be achieved by either arrangement.

It is, therefore, an object of the invention to provide a fluid power driven propping machine having a step length which is relatively independent of its advancing cylinder stroke length.

Another object of the invention is to provide in a travelling propping machine an advancing mechanism which can readily be adapted for use with existing conventional propping frames.

Still another and further object of the invention is to provide a propping machine which can readily be combined with other similar machines so as to support extended roof areas associated with relatively wide strip mining excavations.

.Other and further objects and advantages of the invention will appear in, or become evident from the following detailed description and accompanying drawings wherein:

FIG, 1 is a perspective view of a basic parallelly progressing propping machine in accordance with the invention.

FIG. 2 is a schematic plan view of the basic embodiment of FIG. 1, showing six typical positions of such a propping machine during the advancing procedure.

FIG. 3 is a plan view of another embodiment of the invention wherein the actuating cylinder is aflixed to one of the propping frames and its associated piston shaft is releasably clamped to a guide rail affixed to the other propping frame.

FIG. 4 is a plan view of a propping machine having an advancing mechanism similar to that of FIGS. 1 and 2, but with a short stroke actuating cylinder and a long guide rail, and wherein one of the propping frames has a single prop member.

FIG. 5 is a plan view of a further embodiment of the invention, showing a propping machine having three propping frames, two of which are parallelly advanceable along guide rails alfixed to a third propping frame, and showing a typical arrangement of a plurality of such propping machines interconnected so as to provide roof support over a relatively wide excavation path.

Referring now to FIG. 1, the hydraulically driven propping machine 10 is provided with a pair of conventional propping frames 11 and 11, which can be extensibly jacked to support the roof surface of an excavation (not shown). Each of the frames 11 and 11 has a base member 12 which is adapted to rest upon a base surface, such as the floor of an excavation (not shown) At least one prop jacking member 13 is provided for each of the base members 12, and in the embodiment of FIG. 1, two jacking members 13 are provided for each base member 12.

Each of the jacking members 13 are affixed at one end to their associated base member 12 and at the other end to a cap member 14. The cap members 14 are adapted to bear against the roof surface and cooperate with the jacking members 13 and base members 12 to support said roof surface when the jacking members are extended. If desired, articulating linkages 15 can be provided between the cap 14 on the same base members 12, so as to prevent rotation of said individual caps 14.

The jacking members 13 may be slidably extended and retracted by any suitable conventional means. However, as indicated by FIG. 1, the jacking members 13 are in the form of a hydraulic jack having a cylinder sleeve 16 and a piston column 17, said piston 17 being slidably driven in the sleeve 16 by means of hydraulic fluid supplied to the interior of said sleeve 16 by the lines 18.

A guide rail 19 is fastened at the ends 20 and 21 to the base member 12 of the frame 11, by means of the leaf springs 22. A double-acting linear-acting actuator 23, having a cylinder 24 and double-acting piston 25 which is afiixed to a shaft 26 extending through and beyond the ends 27 and 28 of said cylinder 24 is provided for advancing the frames 11 and 11. The cylinder 24 is slidably connected to the guide rail 19 by the sliders 29. Clamping means 30, associated with each of the sliders 29, are provided for clamping the cylinder 24 to the guide rail 19. The clamping means 30 can be any suitable conventional clamping means, or as shown, hydraulically operated clamping means which can be operated by hydraulic fluid supplied 'by the lines 31. It is essential that the clamping means 30 be so constructed as to permit the cylinder 24 to be selectively clamped (and released) to the guide rail 19, as required in the frame advancing procedure hereafter described.

The piston shaft 26 is fixedly connected at its ends 32 and 33 to the base member 12 of the frame 11 by means of the leaf springs 22, similar to those used for connecting the guide rail 19 to its associated base member 12.

The operation of the propping machine is best explained by referring to FIG. 2, which illustrates six typical positions assumed by the frame 11 and the linear actuator 23 when the frame 11 is advanced. In position A, the frame 11' is shown initially displaced parallel and t0 the rear of the frame 11, with said frames 11 and 11' being locked and supporting the roof, as is indicated by the circles containing X. (Each circle represents a jacking member 13 in the machine 10, an empty circle designating that the jacking member 13 has been retracted and that its corresponding frame 11 or 11 is released from supporting the roof, and can move in response to the actuator 23.)

Also, as indicated in position A, the cylinder 24 is pushed to the end 21 (rear) of the guide rail and clamped thereto (indicated by X), with the poston 25 being in abutting contactWi-th the rear end 28 of said cylinder 24. In order to move the frame 11 from position A to position B, hydraulic fluid is applied at the rear end 28 of the cylinder 24 after the prop jacking members 13 of frame 11' have been released, and thus the piston 25 and its associated frame 11 is driven forward by an amount equal to one cylinder 24 stroke length, as indicated in position B where the piston 25 abuts against the forward end 27 of the cylinder 24.

When the frame 11 is in position B, the cylinder 24 is unclamped (indicated by 11) and hydraulic fluid is ap plied to its forward end 27 thereby causing said cylinder 24 to slide along the guide rail 19 to the position indicated in C. It should be noted that it is not necessary to restrain the frame 11' when the cylinder 24 is moved along the guide rail 19, as aforesaid, because the inertia of the frame 11 is assumed to be relatively large in comparison to any frictional forces which are transmitted by the sliding cylinder 24, so that no substantial backward movement of the frame 11 occurs.

To advance the frame 11 from the position C to that of D, the cylinder 24 is clamped to the guide rail and hydraulic fluid is applied at the rear end 28 of said cylinder 24, thereby advancing the piston 25 and its connected frame 11 by one stroke length, as indicated therein.

To advance the frame 11" from the position D to that indicated by F, the cylinder 24 is unclamped and advanced on the guide rail 19 as previously described so that the cylinder 24 assumes the position shown in E. This position corresponds to that in which any further forward movement of said cylinder 24 is precluded by the forward end of said guide rail 19, and hence it is not necessary to clamp the cylinder 24 when the piston and frame 11' are advanced to position F. Position F corresponds to the maximum forward position of the frame 11'. While the total possible travel of the frame 11' is its displacement between positions A and F, the step length can be considered as the displacement between positions -B and F, since at B the frames 11 and 11' are on a common reference line.

It is to be understood that the foregoing detailed description relating to the advancement of the frame 11 has been presented by way of example, and that should it be desired to advance the frame 11, a substantially similar procedure is to be followed, wherein the frame 11 is locked in position and frame 11 is released. Such a procedure would be obvious to one skilled in the art, in view of the foregoing description, and accordingly, to avoid unnecessary repetition, is omitted herein.

A propping machine 10a, constructed in accordance with another embodiment of the invention, is shown in FIG. 3. The operation of the machine 10a is basically similar to that as previously described in connection with the machine 10 of FIGS. 1 and 2. However, the machine 10:: differs structurally in that the cylinder 24a is aflixed to a relatively short propping frame 11a and its associated piston 25a is mounted on a shaft 26 which is slidably connected to a guide rail 19a, said guide rail 19a being fixedly connected to a long frame 11a. Clamping means 30a, similar to the clamping means 30 used for clamping the cylinder 24 to the guide rail 19 in the machine 10, are provided for clamping the ends 32a and 33a of the piston shaft 26a to the guide rail 19a. As in the operation of the machine 10, the clamping means 30a can be hydraulically operated, and synchronized with the cylinder 24a hydraulic controls (not shown) so as to selectively clamp and release the piston shaft 26a with respect to the guide rail 19a.

When it is desired to advance the short frame 11a in the forward direction, it is released and the long frame 11a is locked in place by its jacking members 13a, and with the piston shaft 26a clamped to the guide rail 19a, the cylinder 24a is driven forward to the limit of its stroke. The piston shaft 26:: is then unclamped and driven forward along the guide rail 19a until limited by the cylinder 24a, and then it is locked. This procedure is repeated until the piston shaft 26a is driven all the way forward on the guide rail 19a and the cylinder 24a is advanced as far forward as possible with the shaft 26a against the forward end 20a of the guide rail 19a. Advancement of the long frame 11a is accomplished in an obviously similar manner.

FIG. 4 which shows a propping machine 100, having the same propping frame advancing mechanism as the machine 10 previously described in connection with FIGS. 1 and 2, illustrates that the short frame 11b and long frame 11b combination of FIG. 3 may be used also with the type of advancing mechanism wherein the cylinder 24b is clamped to a guide rail 19b on the long frame 11b, and the piston shaft 26b is afiixed to a short frame 11b.

FIG. 5 illustrates a further embodiment of the invention as represented by the propping machines 10d, and shows a typical example of how a plurality of machines 10d can be connected together so as to provide roof support over a relatively Wide excavation path. The arrangement of machines 10d as shown therein is particularly adapted for use in strip mining operations wherein a coal plane 34 removes coal from along a cleavage plane wall 35, disposing said removed coal upon a conveyor 36, to be transferred to cars (not shown) and removed from the mining area. The coal plane 34, conveyor 36 and associated propping machines 10d are located in an excavated area between a waste side wall 37 of collapsed rock, and the cleavage plane wall 35.

Referring now to the individual propping machines 10d shown in FIG. 5 a stationary propping frame 38 is ex-tensibly jacked to support the roof and is thereby locked in place. The stationary frame 38 is provided with a pair of parallelly extending guide rails 39, for guiding the parallelly advanceable propping frames 11d. Each frame 11d is provided with an affixed cylinder 24d and an associated piston 25d and piston shaft 26a, similar to those of the embodiment described previously in connection with FIG. 3. The piston shafts 26d are slidably connected to the guide rails 39, and are provided with clamping means 30 d so as to be capable of being selectively clamped to said guide rails 39. The individual frames 11d can be advanced, or retracted independently of each other by means of their associated hydraulically powered cylinder-piston actuators by using the procedures described previously herein.

If desired, a propping frame (not shown) having appropriate guiding means for the frames 11d may be substituted for the combination of the stationary propping frame 38 and extending guide rails 39.

Coupling members 40 can be used, if desired, to connect a plurality of machines 10d together with their stationary frames 38 substantially collinear and their ad vanceable frames 11d mutually parallel.

As the excavation progresses, the stationary frames 38 can be released and moved forward while the frames 11d support the roof.

With the interconnected machines 10d, it is preferable that the stationary frames be moved forward in unison so that a substantially uniform waste side wall 37 of collapsed rock is maintained.

If desired, an advancing device 41 for the conveyor 36 may be attached to the forward ends 42 of the guide rails 39 in a conventional manner.

The guide rails 39 may also extend beneath the conveyor 36 if other advancing means are provided for said conveyor 36. Also, if desired, the guide rails 39 may be disposed near the roof, or be attached 'at any suitable location on the stationary frame 38.

It should be noted that the random positions of the various frames 11d as shown in FIG. are solely for purposes of illustration and are intended to indicate that said frames 11d may be displaced independently of each other.

What is claimed is:

1. A hydraulically driven travelling propping machine which comprises:

(a) a pair of propping frames, each of said propping frames having a base member which is adapted to rest upon a base surface, at least one prop jacking member, and a cap member, each prop member being affixed at one end to the base member, and at the other end to the cap member, said cap member being adapted to bear against -a roof surface and cooperate with the prop members and base member to support said roof surface when said prop members are extensibly jacked;

(b) a guide rail fastened to one of said propping frames;

(c) a double-acting linear actuator, said actuator having a hydraulic cylinder, 21 double-acting piston disposed within said cylinder, said piston being affixed to a shaft extending axially through and beyond the ends of said cylinder;

(d) means for slidably connecting and selectively clamping the actuator cylinder to the guide rail; (e) means for connecting the ends of the piston shaft to the other propping frame; and,

(f) means for control-ling the flow of hydraulic fluid to the actuator cylinder whereby a selected propping frame which has been released from hearing engagement with the roof surface can be translated linearly with respect to the other propping frame which is supporting said roof surface and is thereby locked in place.

2. A hydraulically driven travelling propping machine which comprises:

(a) a pair of propping frames, each of said propping frames having a base member which is adapted to rest upon a base surface, at least one prop jacking member, and a cap member, each prop member being affixed at one end to the base member, and at the other end to the cap member, said cap member being adapted to bear against a roof surface and cooperate with the prop members and base member to support said roof surface when said prop members are extensibly jacked;

(b) a guide rail fastened to one of said propping frames;

(c) a double-acting linear actuator, said actuator having a hydraulic cylinder, a double-acting piston disposed within said cylinder, said piston being affixed to a shaft extending axially through and beyond the ends of said cylinder;

(d) means for slidably connecting and selectively clamping the ends of the piston shaft to the guide rail;

(e) means for fixedly connecting the actuator cylinder to the other propping frame; and,

(f) means for controlling the flow of hydraulic fluid to the actuator cylinder whereby a selected propping frame which has been released from bearing engagement with the roof surface can be displaced linearly with respect to the other propping frame which is supporting said roof surface and is thereby locked in place.

3. A hydraulically driven travelling propping machine 5 which comprises:

(a) a pair of propping frames, each of said propping frames having a base member which is adapted to rest upon a base surface, at least one prop jacking member, and a cap member, each prop member being affixed at one end to the base member, and at the other end to the cap member, said cap member being adapted to bear against a roof surface and cooperate with the prop members and base member to support said roof surface when said prop members are extensibly jacked;

(b) a pair of guide rails, each guide rail being fastened to a propping frame;

(c) a double-acting linear actuator, said actuator having a hydraulic cylinder, a double-acting piston disposed within said cylinder, said piston being aflixed to a shaft extending axially through and beyond the ends of said cylinder;

(d) means for slidably connecting and selectively clamping the ends of the piston shaft to one of the guide rails;

(e) means for slidably connecting and selectively clamping the actuator cylinder to the other guide rail; and,

(f) means for controlling the flow of hydraulic fluid to the actuator cylinder whereby a selected propping frame which has been released from hearing engagement with the roof surface can be displaced linearly with respect to the other propping frame which is supporting said roof surface and is thereby locked in place.

4. A hydraulically driven travelling propping machine which comprises:

(a) a stationary propping frame having a base member which is adapted to rest upon a base surface, at least one prop jacking member, and a cap member, with each prop member being alfixed at one end to the base member, and at the other end to the cap member, said cap member being adapted to bear against a roof surface and cooperate with the prop members and base member to support said roof surface when said prop members are extensibly jacked;

(b) a plurality of guide rails each afiixed at one end to said stationary propping frame, and extending laterally therefrom;

(c) a plurality of movable propping frames, each substantially similar to the stationary frame, the number of said propping frames corresponding to the number of guide rails;

(d) a double-acting linear actuator for each movable propping frame other than the stationary frame, each actuator having a hydraulic cylinder which is fastened to a corresponding movable propping frame, and a double-acting piston disposed within said cylinder, said piston being affixed to a shaft extending axially through and beyond the ends of said cylinder;

(e) means for slidably connecting and selectively clamping the ends of the piston shafts to their corresponding guide rails; and,

(f) means for controlling the flow of hydraulic fluid to the individual actuator cylinders whereby their respectively associated movable propping frames can be displaced linearly and independently with respect to each other and the first propping frame when the stationary propping frame is locked in place and supporting the roof surface and said propping frames which are to be displaced are released from bearing engagement with said roof surface.

5. The propping machine of claim 4 wherein the guide rails are disposed in parallel spaced relation to each other.

6. A ganged multiple frame propping machine which comprises:

(a) a plurality of travelling propping machines according to claim 5, each of said propping machines being disposed so that their movable propping frames are displaceable in mutually parallel directions and their respective stationary propping frames are in substantially collinear spaced relation; and,

(b) a rigid connecting member fastened to each of said stationary propping frames so as to maintain the aforesaid collinear spaced relation.

7. The propping machine of claim wherein an actuator is secured to the guide rails, said actuator being disposed at the extremities thereof and cooperatively connected to a conveyor to displace said conveyor in relation to the stationary propping frame of said machine.

8. The propping machine of claim 4 wherein the guide rails extend beneath the conveyor.

9. The propping machine of claim 1 wherein hydraulic means are provided for selectively clamping the actuator cylinder to the guide rail.

10. The propping machine of claim 2 wherein hydraulic means are provided for selectively clamping the piston shaft to the guide rail.

11. The propping machine of claim 3 wherein hydraulic means are provided for selectively clamping the actuator cylinder and piston shaft to their respective guide rails.

12. A travelling propping machine for supporting a roof surface, which comprises (a) a pair of propping frames supported by a base surface, each of said propping frames being selectively extensible in relation to said base surface for supporting the roof surface, said frames being locked in relation to the base surface when extended to support the roof surface and slidably moveable along said base surface otherwise;

(b) a linear actuator having two-drive members disposed for limited stroke movement relative to each other along a common linear path when the actuator is energized, one of said drive members being fixedly connected to one of said propping frames, and the other of said drive members being slidably connected to the other of said propping frames for limited movement relative thereto along said path;

(c) means for selectively locking and unlocking said slidably connected drive member to its associated propping frame to respectively preclude and permit relative movement therebetween; and,

(d) means for selectively energizing said linear actuator to move one propping frame at a time and in an unlocked condition relative to the other propping frame in a locked condition through stepwise distances limited by the stroke of said actuator, and to repeatedly advance said slidably connected drive member relative to its associated propping frame from the end limit position of one stroke to the starting position of the next stroke to accommodate progressive movement of said propping frames along said path.

References Cited 7 UNITED STATES PATENTS 3,106,825 10/1963 Barall et al 61-45.2 X 3,241,323 3/1966 Grisebach 6l45.2

FOREIGN PATENTS 1,340,145 9/1963 France.

883,407 11/1961 Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner.

JACOB SHAPIRO, Examiner. 

1. A HYDRAULICALLY DRIVEN TRAVELLING PROPPING MACHINE WHICH COMPRISES: (A) A PAIR OF PROPPING FRAMES, EACH OF SAID PROPPING FRAMES HAVING A BASE MEMBER WHICH IS ADAPTED TO REST UPON A BASE SURFACE, AT LEAST ONE PROP JACKING MEMBER, AND A CAP MEMBER, EACH PROP MEMBERR BEING AFFIXED AT ONE END TO THE BASE MEMBER, AND AT THE OTHER END TO THE CAP MEMBER, SAID CAP MEMBER BEING ADAPTED TO BEAR AGAINST A ROOF SURFACE AND COOPERATE WITH THE PROP MEMBERS AND BASE MEMBER TO SUPPORT SAID ROOF SURFACE WHEN SAID PROP MEMBERS ARE EXTENSIBLY JACKED; (B) A GUIDE RAIL FASTENED TO ONE OF SAID PROPPING FRAMES; (C) A DOUBLE-ACTING LINEAR ACTUATOR, SAID ACTUATOR HAVING A HYDRAULIC CYLINDER, A DOUBLE-ACTING PISTON DISPOSED WITHIN SAID CYLINDER, SAID PISTON BEING AFFIXED TO A SHAFT EXTENDING AXIALLY THROUGH AND BEYOND THE ENDS OF SAID CYLINDER; (D) MEANS FOR SLIDABLY CONNECTING AND SELECTIVELY CLAMPING THE ACTUATOR CYLINDER TO THE GUIDE RAIL; (E) MEANS FOR CONNECTING THE ENDS OF THE PISTON SHAFT TO THE OTHER PROPPING FRAME; AND, (F) MEANS FOR CONTROLLING THE FLOW OF HYDRAULIC FLUID TO THE ACTUATOR CYLINDER WHEREBY A SELECTED PROPPING FRAME WHICH HAS BEEN RELEASED FROM BEARING ENGAGEMENT WITH THE ROOF SURFACE CAN BE TRANSLATED LINEARLY WITH RESPECT TO THE OTHER PROPPING FRAME WHICH IS SUPPORTING SAID ROOF SURFACE AND IS THEREBY LOCKED IN PLACE. 